摘要
利用同一岩块不同方向加工的2组砂岩试样,进行完整试样常规三轴压缩试验之后,对不同直径的孔道试样进行了内孔压力为0,外围压为40 MPa的压缩,分析非均匀应力分布对试样承载能力和变形破坏特性的影响.轴向垂直于层理面的试样具有横观各向同性,纵波速度、杨氏模量和强度都较低,完整试样和孔道试样围压下压缩破裂成形状几乎相同的2块;在外围压40MPa下轴向压缩,外径50 mm内径6 mm的孔道试样强度可以超过完整试样,而内径25 mm的孔道试样发生轴向失稳,低于单轴压缩强度.轴向与层理面夹角约为79.5°的试样,具有显著的各向异性,完整试样破坏复杂,而孔道试样因内部自由面提供滑移方向,以完整圆锥破裂;沉积弱面与试样的破坏没有直接的关联.对实验用砂岩而言,平行于层理方向黏结力较小,而不同层面之间的颗粒尺度差异引起摩擦系数增大;试样中层理面的倾向不同,强度特征和破坏形式也就不同.
In order to study the effect of non-uniform stresses on failure,deformation and strength,two groups of solid and hollow cylindrical specimens machined from two directions of one sandstone block were compressed under confining pressure.One specimen,of which the axis was perpendicular to bedding,was transverse isotropic and had lower longitudinal velocity,Youngs modulus and strength.The solid and hollow cylinders were cracked into two parts with nearly the same shape when they were compressed under confining pressure.The strength of hollow cylinder with inner diameter of 6 mm may be higher than the solid one under confining pressure of 40 MPa;however the strength under confining pressure of 40 MPa of hollow cylinder with inner diameter of 25 mm may be lower than the uniaxial compression strength for the compression instability appeared in axial direction.The other specimen,of which the axis declined 79.5° to the sedimentary plane,was anisotropy and the solid one cracked with complicate form;however the hollow cylinder failed with the complete cone for the free slipping direction provided by the inner hole.The failure style was not relative to the sedimentary weak faces in the specimens.The cohesion of the sandstone was lower along the sedimentary plane but the internal friction angle was higher for the various grain sizes in various sedimentary planes,which results in the different properties of specimens with different direction of its axis to bedding.
出处
《河南理工大学学报（自然科学版）》
CAS
2009年第5期626-635,共10页
Journal of Henan Polytechnic University（Natural Science）
基金
国家自然科学基金资助项目(10572047)
关键词
岩石力学
砂岩层理
孔道试样
非均匀应力
强度和变形
破坏形式
rock mechanics
sandstone bedding
hollow cylinder
non-uniform stresses
strength and deformation
failure style
